School me on the differences between a 318 Wide Block and a Regular 318

My friend purchased a 1957 Plymouth "Custom" Suburban this week. The original engine and transmission were gone, but it does have a 1957 318 Wide Block in it from a another Plymouth along with a 1956 Plymouth Transmission. They are supposed to be a good engine and transmission. Neither one of us is knowledgeable on the differences between a 318 Wide Block and I guess a regular 318. We do know that the Wide Block really does mean WIDE! Would someone please educate us on this? I am not a Mopar man, but I do like them and this is his first time of having an old Mopar his self. Thanks in advance.

 

318a (commonly called the wide-block 318) is one of the engines in the Poly family. They were made from the mid '50s through '66.

The 318 LA is part of the Mopar small block line, and the two do not share many parts at all.

Let's see the Suburban! I've got a '57 2dr Suburban myself.

 

318-easy to find speed parts for..
318 wide block(poly) not easy to find speed parts for.. I have a poly in my 38 plymouth pickup..I just found a 3 two barrel intake for it with carbs after looking for a long time..... Jason.

 

what about headers???they hard to get? i bought the fury "golden turd" and was thinkin of runnin headers....
glad ya started this thread....i am in need of a learnins on theze here polys myself

 

I had a 318 poly in my 59 plymouth, stumbled across a aftermarket 2x4 intake for it, so we pulled the motor and completely rebuilt it to handle the gas ( won't do that again, way to expensive ) but it ran hard. I think there very cool motors but like all vintage engines there expensive to rebuild. Had a small block 318 in a 71 Satellite when I was in high school, put a 4 bbl, and headers on it and it ran great. Beat the snot out of it till it had bout a 150,000 miles onit. Sold it and still saw it running around town for a while. I think the small block 318's are a great motor and you can still buy parts for them fairly cheap. Gary

 

the poly (thru 1966) and wedge (67-up) 318 bare blocks are the same size, you'd be hard pressed to tell them apart just looking at them. But, the poly heads are shaped differently so they stick out the sides further, that's how it got the name "wide block". Different exhaust....along with almost everything else.

56 plymouth had two completely different poly V8s, the early 270 and the later 277. The 277 looks just like the poly 318.

 

There is some interchangeability between the two engines; a Mopar lover friend of mine used a forged crank from a wide block 318 in an LA style 318, and the timing chain and gears will interchange if you use all three pieces.

 

Use the search function--there are several old posts on Polys/polysphericals. 4bbl intakes are getting big money these days, but 3x2's can be had cheaper. Bottom end parts are similar/same to '67-later 318's, top end not so much. Motor mounts are the same as LA 318 (pre-Magnum). 318 Poly Stroker motors are popular, but they're expensive to build. With a 2 BBL, a stock Poly is good on gas, have good bottom end torque, and are bulletproof (my 4300 lb '66 could still squawk the tires with 156K on it...).

Header flanges (plasma cut) show up on EBay fairly often. The only pre-made headers I've heard of were $450 and supposedly a pain to put on due to some of the lower bolt locations. I'm sure Gary P. and Abomination will jump in on this convo too--they both have experience with Poly's.

 

I'm the webmaster at the Polyspherical Engine Association.

Just check out the site, dude:
http://www.geocities.com/polyman64

There you'll find the World's largest (and best) list of Poly speed equipment. A LOT of parts swap with an LA 318 - like PRACTICALLY THE ENTIRE BOTTOM END.

Also, hop on and visit us at the 318 Poly Yahoo Group:
http://autos.groups.yahoo.com/group/318poly/

And the Poly Forum at Diamondback Engines:
http://www.diamondbackengines.com/forums/index.php/board,6.0.html

There you'll find the World's authorities on the 318 Poly, with answers as close as posting a question. You can also search the forums there.

~Jason

 

Hell yeah, I'm jumpin' in - I jumped into this pool a long time ago.

~Jason

 

It's easy!

The valve covers on the Poly are scalloped at the bottom, and have two center bolts.

~Jason

 

I was talking about bare blocks looking the same. no valve covers to look at, eh?

the term "wide block" can be confusing, because a poly block and a wedge block are exactly the same width. It's all in the heads! should be called the "wide head" engine.

 

I really appciate all the good Info on this topic. I will pass this Info on to my friend as well. I will try to get him to a computer and try to get a few pictures of the Plymouth on to this thread. By the way, hios Plymouth Suburban is a 9-passenger wagon too! Does anyone have a Pictures of 1957-1959 Plymouths that they might want to put on this thread so he can get a few ideas on just how he might want to go with his "NEW" ride? It can be pictures of Plymouth wagons or cars. At this point, he is thinking Wide Whites and Chrome Reverse wheels. We have even discussed how to run the exhaust without it coming back in when the windows are down. I have a 1962 Belair wagon myself, and I know that when the back tailgate window is down, the exhaust fumes will come right back in on you most of the time. Anyway, any pictures or more Info on the is appreciated! Thanks again!

 

I will argue with the expert here Jason, cos my 1960 Poly has three bolts holding the valve cover down and my Edelbrock covers have three holes to match!
I will email you a pic of the engine cos I can't post pics here-not smart enuff!

swifty

 

On my 66 picup after the origanal 318 poly gave up, I was lookin to put in the later 318 and only after I put in a replacement poly did I find out that you could bolt in the LA 318 to the same trans!!!!...Roach.

 

Oh crap, yes - you are exactly right. There are differences, but they're so subtle that if you don't know where to look or what to look for you'd miss 'em.

Especially with a '62 - '66 ('67 in Canada) block - they have the same bellhousing as an LA motor!

There's talk of folks that have actually done a head swap... the info is on the Yahoo Group or the Poly Forum - possibly both. I had dismissed it as BS initially, but sure enough, it's been done.

~Jason

 

Are you sure it's a 318 Poly? They have two bolts:



Even the Edelbrock:


What's the CID of your poly? What's it from?

~Jason

 

3 bolts, Hemi based Poly. Intake like a LA 318, or intake & valley cover?

 

Exactly my thoughts.

I was waiting for a little more info before I drew that conclusion. Hell, could've been something I'd never heard of before... I never claimed to be the end-all, be-all, and there's always something new to learn!

 

Man... you're right!

Here's the pic, folks!

A long time ago I learned that just because it's not in your personal experience, it doesn't mean it ain't so - and if you remain open to this, you're also open to learning a bunch of stuff you didn't know before, or changing your perspective on exactly what you thought was and wasn't possible before!

Turns out '57 - '62 heads have 3-bolt valve covers, and the '62 - '66 ('67 in Canada) heads have only 2-bolt valve covers.

Those are like $450 valve covers there, Swifty!!!! Niiiice!!!!!

~Jason

 

That poly was a 313 Canadian out of a Dodge truck. It was rebuilt to 318 specs and timing cover and water pump were changed to the car version.
Re the valve covers I saw a set on eBay go for over $800 a few months ago!

swifty

 

If it was "Hemi-based" out of a Dodge, it's not the same engine. The 318 "A" engine was Plymouth only.

 

heres interchangability list, check out the yahoo poly 318 group, anything you need to know can and will be answered there. now who in here has set up 3 94's w/ the p600 intake? i have the carbs done and the intake, havent gotten past that. (extended throttle shafts, idle circuits blocked off on outboard carbs, along w/ choke plates removed same carbs, and 6.5 power valves) contact me if you can. thanx, Sean (and yes the 3x2 question of mine will be asked there, but theres more experience w/ 3x2's here, all the help i can get i'll take)

Building a 318 Polyhead Motor
LA and A Interchange
A lot of parts interchange between the polyspherical A 318 and the LA series of motors (318, 273, 360, 340), including:
<DIR><DIR>Thermostat
Thermostat housing
Internally balanced 273-318-340 harmonic balancers
Valve springs, retainers and keepers
Main bearings (NOT 360 though)
Rod bearings
Crankshafts (reground 360's included)
Flywheel
Starter, both standard and high torque
318 LA ring set
timing chain and sprocket
fuel pump
oil pump
oil pan (not 360)
distributor pump drive gear
distributor, standard points or electronic
</DIR></DIR>
Though reported as interchangable in several references, apparently the timing covers are not the same.

 

Craig Fountain makes a thick set of finned aluminum valve covers for the poly, albeit in the 2-bolt version.

Still, I love the Edelbrock ones. That was the reason I found a foundry - the one that Charlie at Vintage Speed uses... I wanted to make a "factory authorized" reproduction part. I'd even talked to Edelbrock about it, but I went through a kind of crappy divorce and it got lost in the shuffle.

I'll take up the flag again one day... until then though, folks will have to keep lookin'.

Have you heard about the 392 Hemi to 318 Poly intake adapters?
http://www.diamondbackengines.com/forums/index.php?topic=766.0

~Jason

 

Depends on the year. The LA 273 and a think 67 LA 318 share the timing cover with the poly. I know the 273 did.

 

W/P is same except radiator outlet is on opposite sides.

 

LOL! That's a list I made over the course of 6 hours or so using the '67 & '66 parts books at the local MoPar dealer back in like '98.

It's been bastardized and miscredited over the years, but I made the first, as posted on the old Polyspherical Engine Association site.

It may well have been me who directed you here...

I have a P600. Hell, it's right here on y desk. Over the yers I've lost money, etc, but never interest. I gave up on using 3-bolt carbs years ago in favor of 4-bolt ones. And although a 4-bolt carb version of the P600 exists, I'm working with what I've got, which is a huge collection of Stromberg WWs and Carter 2-bbls that were stock on the 318 Poly.

The back two studs fit the 4-bolt carbs, but you'll have to center punch and tap the front two holes, and add some bar stock or something that's been cross drilled over the front bolts before you tighten it down to avoid warpage of the carb base. Of course, you could use Speedway's 3-bolt to 4-bolt carb adapters, but where's the fun in that?

Run the middle carb stock, and then the outer ones get tricky. While you can epoxy shut the idle circuit at the bleeder screws, it'll still allow some air to bleed through. Make sure the outer carbs have no choke or power valve, and file down the butterflies to make sure they sit as FLUSH (meaning ALL THE WAY CLOSED) to block all air unless you open 'em. If this could be done well, you wouldn't even have to close off the idle circiut, by the way.

I even have a custom Stromberg WW progressive linkage from the olden days.

My main problem is in having to use some of Vern Tardell's 4" risers for 3-bolt carbs on top of the Speedway adapters in order for the float bowl of the first carb to clear the thermostat housing, negating passenger car hood clearance.

Those are MY woes... Makes me want to hit up 'ol Gary for a 3-bolt P600 to 4-bolt P600 and trade. Like Gary says (and take this to heart), you're better off with the 4-bolt P600 and 3 2GCs anyway.

Seriously.

But the 3 97s that was built for provide the perfect amount of carburetion for an otherwise unmolested 318 ci flow-wise, and any mods to make that 318 have any more ci can be dealt with with a re-jet.

~Jason

 

well you guys got the similarities figured out, but I thought id post a pic of a poly we are putting a 32 sedan right now, edelbrock covers and all.

 

why did you give up on "D" base carbs? i'm new to multi carbs/ 3x2 set ups in general..... old 94/97's or otherwise, i have my 94's (29-32's) rebuilt and hopefully ready, idle circuits are blocked off on outer carbs and center has 6.5 power valve, extended throttle shafts.... but i dont want to go to ripping into this job if its gonna give me fits, right now i depend on this car, but sometimes i cant leave well enough alone. heres some pics....

 

I'm droolin'!

And crap - there's those 3 bolt holes, too! Are the center ones blocked off on those valve covers?

You should totally post this on the 318 Poly Yahoo Group.
http://autos.groups.yahoo.com/group/318poly/

~Jason